ISSN:
1434-1948
Keywords:
Alkynes
;
Polymers
;
1,2,3-Substituted ferrocene
;
Directed ortho metallation
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
A -CH2NMe2 group attached to ferrocene can be used as an ortho/ortho-directing group to selectively synthesize 1,2,3-substituted ferrocenes, which are used as starting materials for novel 1,3-linked ferrocene polymers and oligomers. The Sonogashira coupling reaction of 1-(I),2-(CH2NMe2)-ferrocene with HC≡CSiEt3 results in 1-(C≡CSiEt3),2-(CH2NMe2)-ferrocene (1b), which - following an ortho-lithiation/iodination sequence - is converted into 1-(I),2-(CH2NMe2),3-(C≡CSiEt3)-ferrocene (1d). Removal of the -SiEt3 protective group yields 1-(I),2-(CH2NMe2),3-(C≡CH)-ferrocene, which can be polymerized under Sonogashira conditions to yield a soluble, bimodal ferrocene-acetylene polymer of MW = 3700/7100 and Mn = 4272. To understand the properties of the polymer better and to evaluate the effect of 1,3-substitution on the electronic communication between the metal centers, a divergent-convergent approach was used to synthesize defined di-, tri- and tetranuclear ferrocenes. Accordingly, 1d was cross-coupled with 1-(CH2NMe2),2-(C≡CH)-ferrocene to give [2-(CH2NMe2)-ferrocene-1-yl]-C≡C-[2-(CH2NMe2),3-(C≡CSiEt3)-ferrocene-1-yl] (2a). Removal of the protective group in 2a led to [2-(CH2NMe2)-ferrocene-1-yl]-C≡C-[2-(CH2NMe2),3-(C≡CH)-ferrocene-1-yl] (2b), which was treated with [1-(I),2-(CH2NMe2)ferrocene-3-yl]-C≡C-[2-(CH2NMe2),3-(C≡CSiEt3)-ferrocene-1-yl] (2c) to result in the corresponding tetrameric ferrocene (4a).
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
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